Hello Jeetraj,
Let's call that number x:
five-sixths of a number means (5/6)*x
two-thirds of the same number means (2/3)*x
"The difference between five-sixths of a number and two-thirds of the same number is 4" means:
(5/6)*x - (2/3)*x = 4
convert 2/3 to 4/6 so both fractions can have the same denominator: (5/6)*x - (4/6)*x = 4
So: (1/6)*x = 4
Multiply both sides by 6: x = 24
That number is 24.
Cheers.